Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
Cute Web Phone Number Extractor - It extracts valid phone, fax number, and mobile numbers from a search engine, websites and files.
CallerSmart - CallerSmart is an application that is basically used for the purpose of looking up mystery phone numbers for free.
WhosCall - WhosCall is a reliable caller ID app whose popularity has led to its adoption by many users including international media. You can now manage the numbers calling you regardless of whether they are part of your contact list or not... read more.
NumValidate - Phone number validation REST API. Simple, Free, and Open Source.
Number Guru - Number Guru is an application for smartphone users for the purpose of reverse phone and caller lookup system.